1. Field of the Invention
The present invention relates to a brake system in an electric vehicle having a follower wheel capable of being hydraulically braked by the operation of a brake operating element, and a driving wheel connected to and driven by a motor using a battery as an energy source and capable of being hydraulically braked and regeneratively braked by the operation of the brake operating element.
2. Description of the Prior Art
There are conventionally known brake systems in vehicles driven to travel by an electric motor using a battery as an energy source, in which a braking force corresponding to an engine-braking of a vehicle equipped with an internal combustion engine is exhibited by a regenerative braking with the aid of the motor, and the battery is charged by the resulting electric power, thereby prolonging the possible travel distance of the vehicle.
A brake system in a vehicle comprising driving wheels capable of being hydraulically and regeneratively braked and follower wheels capable of being hydraulically braked is known from U.S. Pat. No. 3,621,929, in which the regenerative braking of the driving wheels and the hydraulic braking of the follower wheels are performed simultaneously and in parallels during an initial braking, and when the regenerative braking force reaches a limit value, the hydraulic braking of the driving wheels is started.
In the vehicle described in the specification of the above patent, a portion of the kinetic energy of the vehicle is consumed by the hydraulic braking of the follower wheels from the initial braking stage having the largest kinetic energy and for this reason, an effect of recovery of the energy by the regenerative braking cannot be exhibited sufficiently and hence, it is impossible to largely prolong the possible travel distance for a single battery charge.